The present invention relates to a ceramic capacitor and particularly relates to plate like ceramic capacitor which is used in a high temperature environment.
Generally, the ceramic capacitor of this type is structured such that electrodes are provided on both surfaces of the plate like ceramic element assembly, and further, a lead terminal is soldered to each of the electrodes. Then, as a conventional electrode, a baked coated electrode or a wet pated electrode made of Ag, Cu or the like, which is a metal easily soldered, is applied or it has been considered to form a baked coated electrode or a wet plated electrode made of Ni, Zn or the like, which is a metal in which the Sn contained in the solder is hardly diffused, is applied.
When the ceramic capacitor having the baked coated electrode or the wet plated electrode made of Ag, Cu or the like is used in a high temperature environment (for example, about 150.degree. C.), the Sn contained in the solder used for bonding the lead terminal diffuses into the electrode so that the bonding strength between the electrode and the ceramic deteriorates. Accordingly, there is a risk of problems such as the dielectric loss of the ceramic capacitor being increased, and corona discharge produced in the gap between the electrode and the ceramic will break the ceramic capacitor.
In the case of the ceramic capacitor having the coated baked electrode or the wet plated electrode made of Ni, Zn and the like, since Sn contained in the solder is hardly discharged, the above troubles do not occur. However, there occurs another problem such that the soldering operation of the electrode is deteriorated. Accordingly, ti becomes necessary to use a chloride flux which has a problem in reliably bonding the lead terminal and to provide another electrode for mounting the lead terminal on the electrode made of Ni, Zn or the like.